ALLOWANCE FOR LOAN AND LEASE LOSSES - Allowance for Loan and Lease Losses on Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending allowance on loans acquired with deteriorated credit quality (ASC 310-30)	$ 46,156	$ 42,835
Ending allowance on acquired loans outside the scope of ASC 310-30	0	0
Ending allowance on covered loans	46,156	42,835	48,112	51,044	31,555	16,493
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending allowance on loans acquired with deteriorated credit quality (ASC 310-30)	17,390	19,160
Ending allowance on acquired loans outside the scope of ASC 310-30	0	0
Ending allowance on covered loans	17,390	19,160
Real estate-commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending allowance on loans acquired with deteriorated credit quality (ASC 310-30)	25,051	21,930
Ending allowance on acquired loans outside the scope of ASC 310-30	0	0
Ending allowance on covered loans	25,051	21,930
Real estate-residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending allowance on loans acquired with deteriorated credit quality (ASC 310-30)	3,217	1,396
Ending allowance on acquired loans outside the scope of ASC 310-30	0	0
Ending allowance on covered loans	3,217	1,396
Installment
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending allowance on loans acquired with deteriorated credit quality (ASC 310-30)	498	349
Ending allowance on acquired loans outside the scope of ASC 310-30	0	0
Ending allowance on covered loans	$ 498	$ 349